Bluetooth chip navigation for cars -- 2

My company runs a car washing business and we provide these service to a specific apartment's residents. It is 3 times a week. The problem we face is that we need to constantly look for the vehicles we have to wash in the car park and that takes up a lot of time. Problems listed below. 1) Takes up lots of time 2) Miss cars due to human error 3) Need to print out car list and mark physically mark them down 4) Need to constantly message the residents if their car has been washed or not 5) New cars may enter the car park and we forget it. We are looking for a cheaper alternative from RFID. Bluetooth technology or any other similar technology that does at a low cost. Install a coin sized chip(small and less visible as possible) on the inside of the vehicle of the car. Approved by residents. A phone app that will detect all these signals and output as vehicle numbers on the phone. The app will show the precise location of the car. The distance from the phone to the car. There are several floors in the car park so it can get a little complicated. Mapping solutions or other solutions proposed will be taken into consideration. After car wash is done customer will receive SMS or notification via customer side app. There will be other smaller details such as swiping left for completed car. auto sms sending. adding photo and a message to the customer by the car washer. time recorded for per car wash..ways to ensure cars are washed and not skipped by car washers. Minimising lack of quality. Eg. car washer spots a car and doesn't wash the car. And we will be able to know...also collect data such as time taken for car to enter..etc..the reason why we use blue tooth is because at underground car parks, there is no 4G/3G or data network.. We need a team to get the best, small and cost saving chip available in the market, and come up with a system to tag these chips..and an android app for the car washers to locate the cars. other technical details such as what if the customer changes cars etc will be discussed later. Desired Skills MySQL Administration, HTML, PHP